Clearance rates of food suspension and food passage rates as a function of temperature in two north-sea bryozoans

The filtration rate has been determined for Electra pilosa and Conopeum reticulum, acclimated at 4 constant temperatures (6°, 12°, 18°, 22°C). Cryptomonas sp. was used as the test food-organism. Temperature affects filtration rate in both bryozoans. Clearance rate, measured at hourly intervals during the course of the experiment, was never uniform. Possibly, temporary reductions in ciliary activities were induced by the artificial conditions under which the experiments were carried out. The results obtained compare well with those reported by Bullivant (1968) on Bowerbankia imbricata, a cosmopolitan ctenostome. Rate of food passage through the alimentary canal is affected by temperature. The present study is the first to demonstrate the effect of temperature on the rate of filtration in bryozoans.